Home Insulation Types: Which Is Best for Your Project?

Insulation R-Values Explained

R-value measures thermal resistance — higher R-value = better insulation. The required R-value depends on your climate zone (DOE zones 1–7) and location in the home. Typical recommendations: Attics R-38 to R-60; walls R-13 to R-21; crawlspaces and basements R-13 to R-30.

Insulation Types Compared

• Fiberglass batts: R-2.9 to R-3.8 per inch. Most common, DIY-friendly, fits standard stud spacing. Requires careful installation to avoid air gaps (which dramatically reduce effectiveness).
• Blown-in fiberglass/cellulose: R-2.5 to R-3.7 per inch. Best for attics and irregularly shaped spaces. Fills gaps and voids that batts leave behind. Cellulose (recycled newspaper) is more eco-friendly; fiberglass lasts longer without settling.
• Spray polyurethane foam (open-cell): R-3.5 to R-4 per inch. Expands to fill all gaps. Excellent air sealing. Open-cell is vapor permeable; good for interior walls.
• Spray polyurethane foam (closed-cell): R-6 to R-7 per inch. Best R-value per inch. Acts as vapor barrier. Structural reinforcement benefit. Most expensive (~$1.50–3.50/sq ft per inch installed).
• Rigid foam boards: R-4 to R-6.5 per inch. Used on exterior walls, basement walls, roof decks. Excellent for continuous insulation reducing thermal bridging through studs.

Best Application by Location

• Attic floor: Blown-in (best coverage) or batts. Target R-49 to R-60 in most climates.
• Walls (new construction): Batts or closed-cell spray foam in framing cavity.
• Rim joists: Closed-cell spray foam (air sealing critical here).
• Basement walls: Rigid foam on exterior or closed-cell spray on interior.